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Manganese (Mn) in Scottish Groundwater

2026-06-24T10:30:01Z

Ajhil: /* Manganese (Mn) in Scottish Groundwater */

{{Underconstruction}}
===Manganese (Mn) in Scottish Groundwater===
'''Background''' 
Excessive Mn concentrations can result in metallic tasting water, staining of clothes, dishes, and products such as paper or plastics, and reduced water pressure and flow in pipes from accumulation of Mn oxides (Sly et al., 1990). They have also been found to have an adverse effect on human health. In adults, exposure to elevated Mn concentrations in drinking water has been associated with manganism, a Parkinson-like disorder, and in children, intellectual function and hyperactive behaviour. Because of the association between Mn intake and neurological effects the World Health Organisation(WHO) current guideline concentration for Mn in drinking water is 0.4 mg l-1 (World Health Organisation, 2008).

===Controls of Mn in groundwater===
[[Image:MnConcentrations.jpg|frameless|center|500px|]]

<center>'''Figure 1'''    Mn concentrations in Scotland. BGS © UKRI.</center>

[[Image:Bedrock aquifer units.jpg|frameless|center|500px|]]

<center>'''Figure 2'''    Bedrock aquifer units. BGS © UKRI.</center>

[[Image:Manganese concentrations.jpg|frameless|center|500px|]]

<center>'''Figure 3'''    Manganese concentrations in groundwater and geology in Scotland. BGS © UKRI.</center>

The occurrence and concentration of Mn in groundwater are controlled by many factors, the main ones being rock geochemistry, water chemistry and microbiological activity. Some rock types, such as mafic and ultramafic rocks, shale, greywacke and limestone, contain high concentrations of Mn, which can lead to elevated concentrations in soil and sediment through weathering processes. Water chemistry, in particular pH, redox potential (Eh), dissolved oxygen (DO), and dissolved organic carbon (DOC), is instrumental in mobilising Mn and controlling its speciation and concentration in the water environment.

===Recent Research on Mn in Scotland===
Research using data by Baseline Scotland [https://nora.nerc.ac.uk/id/eprint/9665/ (Hominik et al. 2010)] assessed the concentrations of Mn in Scottish groundwater, between different aquifer types, and examined the controls on elevated Mn concentrations in groundwater.

This research developed a quality-controlled dataset of groundwater Mn concentrations across Scotland with data for 475 sites.

===Results===
* Analysis of this dataset showed that elevated Mn concentrations (> 0.05 mg/L) occurred in 30% of the groundwater samples (Figure 1), particularly in superficial, Carboniferous, and northern Devonian aquifers (Figures 2 and 3); and 9% of sites had concentrations above the WHO health drinking water limit (0.4 mg/L).
* The principal controls on Mn concentrations in groundwater in Scotland are redox conditions and pH, with some influence from Fe behaviour. Redox conditions exercise the strongest control.
* The results highlight the potential risk of exposure to excessive Mn in drinking water for consumers using private water supplies and indicate the need for appropriate methods for sampling and testing groundwater for Mn not only in Scotland but worldwide.

===References and resources===
Homoncik, S, MacDonald, A M, Heal, K V, Ó Dochartaigh, B É, and Ngwenya, B T. 2010. [https://nora.nerc.ac.uk/id/eprint/9665/ Manganese concentrations in Scottish groundwater], ''Science of the Total Environment'', 408; 2467–2473.

MacDonald, A M and Ó Dochartaigh, B É. 2005. [https://nora.nerc.ac.uk/id/eprint/11335/ Baseline Scotland; an overview of available groundwater chemistry data for Scotland], ''British Geological Survey Commissioned Report, CR/05/239N'', British Geological Survey, Keyworth, Nottingham.

MacDonald, A M, Robins, N S, Ball, D F and Ó Dochartaigh, B É. 2005. [https://nora.nerc.ac.uk/id/eprint/12230/ An overview of groundwater in Scotland], Scottish Journal of Geology, 41; 3–11.

Robins, N S. 2002. [https://nora.nerc.ac.uk/id/eprint/12305/ Groundwater quality in Scotland: major ion chemistry of the key groundwater bodies], ''Science of the Total Environment'', 294; 1–3; 41–56.

Sly, L J, Hodgkinson, M C and Arunpairojana, V. 1990. Deposition of manganese in a drinking water distribution system, ''Applied Environmental Microbiology'', 56; 628–639.

[[category:Groundwater and shale gas]]

===Controls of Mn in groundwater===
[[Image:MnConcentrations.jpg|frameless|center|500px|]]

<center>'''Figure 1'''    Mn concentrations in Scotland. BGS © UKRI.</center>

[[Image:Bedrock aquifer units.jpg|frameless|center|500px|]]

<center>'''Figure 2'''    Bedrock aquifer units. BGS © UKRI.</center>

[[Image:Manganese concentrations.jpg|frameless|center|500px|]]

<center>'''Figure 3'''    Manganese concentrations in groundwater and geology in Scotland. BGS © UKRI.</center>

The occurrence and concentration of Mn in groundwater are controlled by many factors, the main ones being rock geochemistry, water chemistry and microbiological activity. Some rock types, such as mafic and ultramafic rocks, shale, greywacke and limestone, contain high concentrations of Mn, which can lead to elevated concentrations in soil and sediment through weathering processes. Water chemistry, in particular pH, redox potential (Eh), dissolved oxygen (DO), and dissolved organic carbon (DOC), is instrumental in mobilising Mn and controlling its speciation and concentration in the water environment.

===Recent Research on Mn in Scotland===
Research using data by Baseline Scotland [https://nora.nerc.ac.uk/id/eprint/9665/ (Hominik et al. 2010)] assessed the concentrations of Mn in Scottish groundwater, between different aquifer types, and examined the controls on elevated Mn concentrations in groundwater.

This research developed a quality-controlled dataset of groundwater Mn concentrations across Scotland with data for 475 sites.

===Results===
* Analysis of this dataset showed that elevated Mn concentrations (> 0.05 mg/L) occurred in 30% of the groundwater samples (Figure 1), particularly in superficial, Carboniferous, and northern Devonian aquifers (Figures 2 and 3); and 9% of sites had concentrations above the WHO health drinking water limit (0.4 mg/L).
* The principal controls on Mn concentrations in groundwater in Scotland are redox conditions and pH, with some influence from Fe behaviour. Redox conditions exercise the strongest control.
* The results highlight the potential risk of exposure to excessive Mn in drinking water for consumers using private water supplies and indicate the need for appropriate methods for sampling and testing groundwater for Mn not only in Scotland but worldwide.

===References and resources===
Homoncik, S, MacDonald, A M, Heal, K V, Ó Dochartaigh, B É, and Ngwenya, B T. 2010. [https://nora.nerc.ac.uk/id/eprint/9665/ Manganese concentrations in Scottish groundwater], ''Science of the Total Environment'', 408; 2467–2473.

MacDonald, A M and Ó Dochartaigh, B É. 2005. [https://nora.nerc.ac.uk/id/eprint/11335/ Baseline Scotland; an overview of available groundwater chemistry data for Scotland], ''British Geological Survey Commissioned Report, CR/05/239N'', British Geological Survey, Keyworth, Nottingham.

MacDonald, A M, Robins, N S, Ball, D F and Ó Dochartaigh, B É. 2005. [https://nora.nerc.ac.uk/id/eprint/12230/ An overview of groundwater in Scotland], Scottish Journal of Geology, 41; 3–11.

Robins, N S. 2002. [https://nora.nerc.ac.uk/id/eprint/12305/ Groundwater quality in Scotland: major ion chemistry of the key groundwater bodies], ''Science of the Total Environment'', 294; 1–3; 41–56.

Sly, L J, Hodgkinson, M C and Arunpairojana, V. 1990. Deposition of manganese in a drinking water distribution system, ''Applied Environmental Microbiology'', 56; 628–639.

[[category:Groundwater and shale gas]]

Manganese (Mn) in Scottish Groundwater

2026-06-24T10:29:55Z

Ajhil: /* Manganese (Mn) in Scottish Groundwater */

Scotland's aquifers and groundwater bodies

2026-06-24T10:26:02Z

Ajhil: /* Scotland's aquifers and groundwater bodies */

{{Underconstruction}}
==Scotland's aquifers and groundwater bodies==
This report, published in 2015, was written jointly by BGS and the [https://www.sepa.org.uk/ Scottish Environment Protection Agency] (SEPA). The report is written in the form of a manual for those with some technical groundwater (hydrogeological) knowledge, but also includes summaries for non-specialists.

[[Image:Report_Cover1.jpg|frameless|center|350px|]]

<center>'''[https://nora.nerc.ac.uk/id/eprint/511413/ Download the report] for free from the NERC Open Research Archive (NORA).'''</center>

===A comprehensive synthesis===
[https://nora.nerc.ac.uk/id/eprint/511413/ Scotland's aquifers and groundwater bodies] provides an up to date overview of Scotland's aquifers, their hydrogeology and their baseline groundwater chemistry. It also gives an introduction to groundwater and groundwater management in Scotland, and describes the process of delineating groundwater bodies, which are the basis of groundwater management in Scotland under the [[Glossary of groundwater and groundwater-related terms#Water Framework Directive | Water Framework Directive]].

===Scotland's vital groundwater===
Groundwater occurs almost everywhere in Scotland. It is a key water source for drinking, agriculture, industry (including the bottled water and whisky sectors), and recreation (including golf course irrigation), and therefore plays an important role in Scotland's economy. Groundwater is also vital to the health of Scotland's environment, supporting surface water ecosystems, helping to dilute and assimilate contaminants, and mitigating flooding.

<center>
<div><ul>
<li style="display: inline-block;"> [[File:Artesian_Borehole.jpg|frameless|left|300px]]</li>
<li style="display: inline-block;"> [[File:Wells_of_Dee2.jpg|frameless|right|330px]]</li>
<li style="display: inline-block;"> [[File:Water_and_Whisky.jpg|frameless|right|300px]]</li>
</ul></div>
</center>

<center>''(top left)'' '''Artesian borehole on Arran. BGS © UKRI.'''</center>
<center>''(centre)'' '''Wells of Dee. BGS © UKRI.'''</center>
<center>''(top right)'' '''Water and whisky from Scotland. BGS © UKRI.'''</center>

===Contact===
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Baseline Scotland: groundwater chemistry data

2026-06-24T10:24:34Z

Ajhil: /* Baseline Scotland data summaries */

{{Underconstruction}}
==Baseline Scotland: groundwater chemistry data==
Collecting new data on groundwater chemistry in Scotland to provide a scientific foundation to Scottish, UK and European water quality policy.

===About Baseline Scotland===
[[Image:Sepa_logo1.jpg|frameless|right|200px|]]
Baseline Scotland is a joint project between BGS and [https://www.sepa.org.uk/ SEPA ]which is providing new groundwater chemistry data for Scotland. This new data provides essential information to sustainably manage Scotland’s water environment, as required by Scottish, UK and European water legislation, (such as the [[Glossary of groundwater and groundwater-related terms#Water Framework Directive | Water Framework Directive)]]. Before Baseline Scotland very little reliable groundwater chemistry data existed, particularly for trace elements.

Systematic groundwater sampling surveys were carried out across all the major bedrock aquifers in Scotland between 2005 and 2011, as well as many superficial aquifers. Standardised sampling techniques were used to characterise the groundwater chemistry in detail and investigate how long since groundwater was recharged from rainfall; how groundwater has interacted with the aquifer rocks; and whether there is any groundwater pollution. The results from most parts of Scotland have already been reported in [[Baseline Scotland reports | detailed reports]]. Summary results for each major aquifer group in Scotland are presented in [[Scotland's aquifers and groundwater bodies | Scotland’s Aquifers and Groundwater Bodies]] (2015). Detailed results for the final areas, and a detailed overview of the baseline groundwater chemistry of Scotland, will be reported soon.

===The aims of Baseline Scotland are:===
* To characterise the natural background groundwater quality in the main aquifers of Scotland, by carrying out new detailed groundwater chemistry sampling.
*To provide a scientific foundation to Scottish, UK and European water quality policy and groundwater management and protection, with an emphasis on the protection and sustainable development of high quality groundwater.

===Outputs===
* Summarised groundwater chemistry data for major bedrock aquifers in Scotland.

===Spatial coverage of groundwater chemistry data: Scotland===
Before the Baseline Scotland project began there was little information on natural groundwater chemistry in Scotland. Existing data was mainly old, of variable quality, limited (often to a few major ions only), and skewed to areas of groundwater contamination, particularly related to mining, and to the more productive Scottish aquifers, in particular the Devonian aquifers of Fife, Strathmore and Morayshire, and the Permian aquifer in Dumfries. Since the start of the Baseline Scotland project, 268 new groundwater samples have been collected from aquifers across Scotland. A further 479 samples collected during other projects since 2001, using equally rigorous sampling techniques to the Baseline samples, have been incorporated into the Baseline dataset.

[[Image:AllBaselineSamples-Nov15.jpg|frameless|center|400px|]]

<center>'''Spatial coverage of Baseline Scotland groundwater chemistry data: for bedrock aquifers (blue circles) and Quaternary aquifers (green squares). Backdrop is 1:625 000 scale geological map.'''</center>

===Baseline sampling===
The Baseline sampling surveys collected new data on groundwater chemistry, stable isotopes and residence times. Rigorous well head measurements (of parameters including dissolved oxygen, redox potential, SEC and bicarbonate) were combined with collecting samples for analysis of major, minor and trace ions; stable isotopes (δH2, δ18O and δ13C); dissolved organic carbon; and where possible, CFC (chlorofluorocarbon), SF6 (sulphur hexafluoride), and other dissolved gases such as CH4 (methane).

* [[Baseline sampling and analysis methodology | Technical details of the Baseline sampling methodology]]

<center>
<div><ul>
<li style="display: inline-block;"> [[File:Baseline_photo3.jpg|frameless|left|285px]]</li>
<li style="display: inline-block;"> [[File:Baseline_photo2.jpg|frameless|right|350px]]</li>
<li style="display: inline-block;"> [[File:Baseline_photo1.jpg|frameless|right|350px]]</li>
</ul></div>
</center>

<center>''(top left)'' '''Measuring wellhead chemistry. BGS © UKRI.'''</center>
<center>''(centre)'' '''Sampling groundwater. BGS © UKRI.'''</center>
<center>''(bottom)'' '''Sampling groundwater. BGS © UKRI.'''</center>

===Baseline Scotland data===
Twelve major bedrock aquifer units have been defined across Scotland, which have distinctly different controls on baseline groundwater chemistry – largely related to geological age and rock type. The baseline groundwater chemistry of each of these aquifer units is reported separately. Click on the data links below to view summaries of baseline groundwater chemistry data already reported for Scotland.
 
[[Image:BaselineBedrock.jpg|frameless|center|350px|]]
<center>'''Major bedrock aquifer units in Scotland, which show distinctly different baseline groundwater chemistry.'''</center>

===Baseline Scotland data summaries===
* [[Aberdeenshire | Aberdeenshire data]]
* [[Midland Valley | Midland Valley data]]
* [[Moray Firth | Moray Firth data]]
* [[Southern Scotland | Southern Scotland data]]
* [[Strathmore | Strathmore data]]
* [[Manganese in Scottish Groundwater | Manganese in Scottish Groundwater]]

A summary of the baseline groundwater chemistry in each major bedrock aquifer in Scotland is presented in [[Scotland's aquifers and groundwater bodies | Scotland’s Aquifers and Groundwater Bodies]].

===Contact===
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

File:Manganese concentrations in groundwater.jpg

2026-06-24T10:17:41Z

Ajhil:

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[[Category:License tags]]

File:Bedrock aquifer units1.jpg

2026-06-24T10:15:18Z

Ajhil:

File:Mn concentrations in Scotland.jpg

2026-06-24T09:44:21Z

Ajhil:

Strathmore

2026-06-24T09:36:18Z

Ajhil: /* Baseline report */

{{Underconstruction}}
===Strathmore===
A total of 48 groundwater samples, collected from boreholes, springs and shallow wells, were used to interpret the chemistry of groundwater in the high productivity Devonian sedimentary aquifer.

[[Image:Samples_Strathmore.jpg|frameless|center|500px|]]

<center>'''Baseline samples in Strathmore; the backdrop is the 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/10299/ Baseline Scotland: the Lower Devonian aquifer of Strathmore] report.

===Baseline data===
'''Main findings''' 
The collection and interpretation of new groundwater chemistry data for the Strathmore area has led to the following conclusions:

* ''The groundwaters of the Devonian aquifer in Strathmore are mainly weakly mineralised'', with TDS concentrations mostly less than 400 mg/l. Groundwaters have near-neutral to slightly alkaline pH values and are for the most part oxygenated, with detectable dissolved oxygen and high redox potentials. As a result, dissolved iron, manganese and ammonium (NH4-N) concentrations are usually low. Water from shallow boreholes and springs is often undersaturated with calcite, but in deeper boreholes, reaction with carbonate minerals in the aquifer is more usual and most of these are saturated with respect to calcite.
* ''Nitrate concentrations'' are often high and nearly one third of the samples exceeded the EC drinking water limit for nitrate of 11.4 mg/l.1 as NO3-N. Under the oxidising conditions, nitrate is a stable solute species across the aquifer and is found at depths in excess of 100 m.
* ''Concentrations of phosphorous'' in groundwater across the aquifer are typically less than 0.1 mg/l. Given the importance of P in controlling eutrophication in surface water, these concentrations in groundwater may be significant.
* ''Increased salinity occurs in groundwater'' in some near-coastal boreholes, most likely as a result of mixing with seawater.
* ''Most trace elements have low concentrations'', in accordance with the neutral pH groundwater conditions. Concentrations of arsenic are relatively high in some groundwaters (up to 8.8 μg/l), though none exceeds the EC maximum permissible value for drinking water of 10 μg/l. Concentrations of uranium reach up to 15.4 μg/l, with the highest concentration just exceeding the WHO provisional guideline value for drinking water of 15 μg/l. Two other exceedances above maximum permissible values for drinking were observed, for nitrite (highest concentration 0.194 mg/l.) and fluoride (highest concentration 3.7 mg/l.).
* ''The chemistry and residence time'' indicators (CFC and stable isotopes) indicate that the groundwaters are largely of young age, being mostly recharged within the last 40 years, with mixing throughout the top 100 m of the aqufier. The young age of the groundwaters means they are vulnerable to contamination.
* ''The most significant groundwater-quality problems'' identified by this survey are:
# The widespread presence of elevated nitrate concentrations in groundwater, which is strongly linked to agricultural activity;
# Elevated phosphate concentrations, which may affect the quality of surface water when discharged to rivers as baseflow.
# The presence of saline water in some near-coastal boreholes, indicating localised saline intrusion. It is not clear to what degree the saline intrusion is natural and to what degree it has been enhanced by over-pumping.
===Data===
* [[Media:Tablestats_summary1.jpg|Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (1 of 2)]]
* [[Media:Tablestats_summary2.jpg|Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (2 of 2)]]
* [[Media:Piperdiagram_majorions1.jpg|Strathmore groundwater — Piper diagram of the major ion chemistry]]
* [[Media:Maps.jpg|Ca, Mg and HCO3 and Cl, SO4, NO3-N — Maps illustrating spatial variation in the concentration]]
* [[Media:Maps2.jpg|Na, K and P and F, Fe and Mn — Maps illustrating spatial variation in the concentration]]

===Baseline report===
Ó Dochartaigh, B. É., Smedley, P., MacDonald, A. M. and Darling, W. G. (2004) [https://nora.nerc.ac.uk/id/eprint/10299/ Baseline Scotland: the Lower Devonian aquifer of Strathmore]. Commissioned Report, CR/06/250N. British Geological Survey.
[[category:Groundwater and shale gas]]

Strathmore

2026-06-24T09:35:50Z

Ajhil: /* Baseline report */

File:Maps2.jpg

2026-06-24T09:34:02Z

Ajhil:

File:Maps.jpg

2026-06-24T09:33:20Z

Ajhil:

File:Piperdiagram majorions1.jpg

2026-06-24T09:32:07Z

Ajhil:

File:Tablestats summary2.jpg

2026-06-24T09:31:37Z

Ajhil:

File:Tablestats summary1.jpg

2026-06-24T09:31:13Z

Ajhil:

Strathmore

2026-06-24T09:30:44Z

Ajhil: /* Data */

{{Underconstruction}}
===Strathmore===
A total of 48 groundwater samples, collected from boreholes, springs and shallow wells, were used to interpret the chemistry of groundwater in the high productivity Devonian sedimentary aquifer.

[[Image:Samples_Strathmore.jpg|frameless|center|500px|]]

<center>'''Baseline samples in Strathmore; the backdrop is the 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/10299/ Baseline Scotland: the Lower Devonian aquifer of Strathmore] report.

===Baseline data===
'''Main findings''' 
The collection and interpretation of new groundwater chemistry data for the Strathmore area has led to the following conclusions:

* ''The groundwaters of the Devonian aquifer in Strathmore are mainly weakly mineralised'', with TDS concentrations mostly less than 400 mg/l. Groundwaters have near-neutral to slightly alkaline pH values and are for the most part oxygenated, with detectable dissolved oxygen and high redox potentials. As a result, dissolved iron, manganese and ammonium (NH4-N) concentrations are usually low. Water from shallow boreholes and springs is often undersaturated with calcite, but in deeper boreholes, reaction with carbonate minerals in the aquifer is more usual and most of these are saturated with respect to calcite.
* ''Nitrate concentrations'' are often high and nearly one third of the samples exceeded the EC drinking water limit for nitrate of 11.4 mg/l.1 as NO3-N. Under the oxidising conditions, nitrate is a stable solute species across the aquifer and is found at depths in excess of 100 m.
* ''Concentrations of phosphorous'' in groundwater across the aquifer are typically less than 0.1 mg/l. Given the importance of P in controlling eutrophication in surface water, these concentrations in groundwater may be significant.
* ''Increased salinity occurs in groundwater'' in some near-coastal boreholes, most likely as a result of mixing with seawater.
* ''Most trace elements have low concentrations'', in accordance with the neutral pH groundwater conditions. Concentrations of arsenic are relatively high in some groundwaters (up to 8.8 μg/l), though none exceeds the EC maximum permissible value for drinking water of 10 μg/l. Concentrations of uranium reach up to 15.4 μg/l, with the highest concentration just exceeding the WHO provisional guideline value for drinking water of 15 μg/l. Two other exceedances above maximum permissible values for drinking were observed, for nitrite (highest concentration 0.194 mg/l.) and fluoride (highest concentration 3.7 mg/l.).
* ''The chemistry and residence time'' indicators (CFC and stable isotopes) indicate that the groundwaters are largely of young age, being mostly recharged within the last 40 years, with mixing throughout the top 100 m of the aqufier. The young age of the groundwaters means they are vulnerable to contamination.
* ''The most significant groundwater-quality problems'' identified by this survey are:
# The widespread presence of elevated nitrate concentrations in groundwater, which is strongly linked to agricultural activity;
# Elevated phosphate concentrations, which may affect the quality of surface water when discharged to rivers as baseflow.
# The presence of saline water in some near-coastal boreholes, indicating localised saline intrusion. It is not clear to what degree the saline intrusion is natural and to what degree it has been enhanced by over-pumping.
===Data===
* [[Media:Tablestats_summary1.jpg|Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (1 of 2)]]
* [[Media:Tablestats_summary2.jpg|Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (2 of 2)]]
* [[Media:Piperdiagram_majorions1.jpg|Strathmore groundwater — Piper diagram of the major ion chemistry]]
* [[Media:Maps.jpg|Ca, Mg and HCO3 and Cl, SO4, NO3-N — Maps illustrating spatial variation in the concentration]]
* [[Media:Maps2.jpg|Na, K and P and F, Fe and Mn — Maps illustrating spatial variation in the concentration]]

===Baseline report===
Ó Dochartaigh, B. É., Smedley, P., MacDonald, A. M. and Darling, W. G. (2004) Baseline Scotland: the Lower Devonian aquifer of Strathmore. Commissioned Report, CR/06/250N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Strathmore

2026-06-24T09:27:59Z

Ajhil: /* Baseline report= */

{{Underconstruction}}
===Strathmore===
A total of 48 groundwater samples, collected from boreholes, springs and shallow wells, were used to interpret the chemistry of groundwater in the high productivity Devonian sedimentary aquifer.

[[Image:Samples_Strathmore.jpg|frameless|center|500px|]]

<center>'''Baseline samples in Strathmore; the backdrop is the 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/10299/ Baseline Scotland: the Lower Devonian aquifer of Strathmore] report.

===Baseline data===
'''Main findings''' 
The collection and interpretation of new groundwater chemistry data for the Strathmore area has led to the following conclusions:

* ''The groundwaters of the Devonian aquifer in Strathmore are mainly weakly mineralised'', with TDS concentrations mostly less than 400 mg/l. Groundwaters have near-neutral to slightly alkaline pH values and are for the most part oxygenated, with detectable dissolved oxygen and high redox potentials. As a result, dissolved iron, manganese and ammonium (NH4-N) concentrations are usually low. Water from shallow boreholes and springs is often undersaturated with calcite, but in deeper boreholes, reaction with carbonate minerals in the aquifer is more usual and most of these are saturated with respect to calcite.
* ''Nitrate concentrations'' are often high and nearly one third of the samples exceeded the EC drinking water limit for nitrate of 11.4 mg/l.1 as NO3-N. Under the oxidising conditions, nitrate is a stable solute species across the aquifer and is found at depths in excess of 100 m.
* ''Concentrations of phosphorous'' in groundwater across the aquifer are typically less than 0.1 mg/l. Given the importance of P in controlling eutrophication in surface water, these concentrations in groundwater may be significant.
* ''Increased salinity occurs in groundwater'' in some near-coastal boreholes, most likely as a result of mixing with seawater.
* ''Most trace elements have low concentrations'', in accordance with the neutral pH groundwater conditions. Concentrations of arsenic are relatively high in some groundwaters (up to 8.8 μg/l), though none exceeds the EC maximum permissible value for drinking water of 10 μg/l. Concentrations of uranium reach up to 15.4 μg/l, with the highest concentration just exceeding the WHO provisional guideline value for drinking water of 15 μg/l. Two other exceedances above maximum permissible values for drinking were observed, for nitrite (highest concentration 0.194 mg/l.) and fluoride (highest concentration 3.7 mg/l.).
* ''The chemistry and residence time'' indicators (CFC and stable isotopes) indicate that the groundwaters are largely of young age, being mostly recharged within the last 40 years, with mixing throughout the top 100 m of the aqufier. The young age of the groundwaters means they are vulnerable to contamination.
* ''The most significant groundwater-quality problems'' identified by this survey are:
# The widespread presence of elevated nitrate concentrations in groundwater, which is strongly linked to agricultural activity;
# Elevated phosphate concentrations, which may affect the quality of surface water when discharged to rivers as baseflow.
# The presence of saline water in some near-coastal boreholes, indicating localised saline intrusion. It is not clear to what degree the saline intrusion is natural and to what degree it has been enhanced by over-pumping.
===Data===
* [[Media:AppinGroup.jpg|Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (1 of 2)]]
* [[Media:AppinGroup.jpg|Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (2 of 2)]]
* [[Media:AppinGroup.jpg|Strathmore groundwater — Piper diagram of the major ion chemistry]]
* [[Media:AppinGroup.jpg|Ca, Mg and HCO3 and Cl, SO4, NO3-N — Maps illustrating spatial variation in the concentration]]
* [[Media:AppinGroup.jpg|Na, K and P and F, Fe and Mn — Maps illustrating spatial variation in the concentration]]

===Baseline report===
Ó Dochartaigh, B. É., Smedley, P., MacDonald, A. M. and Darling, W. G. (2004) Baseline Scotland: the Lower Devonian aquifer of Strathmore. Commissioned Report, CR/06/250N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Strathmore

2026-06-24T09:27:02Z

Ajhil: /* Data */

{{Underconstruction}}
===Strathmore===
A total of 48 groundwater samples, collected from boreholes, springs and shallow wells, were used to interpret the chemistry of groundwater in the high productivity Devonian sedimentary aquifer.

[[Image:Samples_Strathmore.jpg|frameless|center|500px|]]

<center>'''Baseline samples in Strathmore; the backdrop is the 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/10299/ Baseline Scotland: the Lower Devonian aquifer of Strathmore] report.

===Baseline data===
'''Main findings''' 
The collection and interpretation of new groundwater chemistry data for the Strathmore area has led to the following conclusions:

* ''The groundwaters of the Devonian aquifer in Strathmore are mainly weakly mineralised'', with TDS concentrations mostly less than 400 mg/l. Groundwaters have near-neutral to slightly alkaline pH values and are for the most part oxygenated, with detectable dissolved oxygen and high redox potentials. As a result, dissolved iron, manganese and ammonium (NH4-N) concentrations are usually low. Water from shallow boreholes and springs is often undersaturated with calcite, but in deeper boreholes, reaction with carbonate minerals in the aquifer is more usual and most of these are saturated with respect to calcite.
* ''Nitrate concentrations'' are often high and nearly one third of the samples exceeded the EC drinking water limit for nitrate of 11.4 mg/l.1 as NO3-N. Under the oxidising conditions, nitrate is a stable solute species across the aquifer and is found at depths in excess of 100 m.
* ''Concentrations of phosphorous'' in groundwater across the aquifer are typically less than 0.1 mg/l. Given the importance of P in controlling eutrophication in surface water, these concentrations in groundwater may be significant.
* ''Increased salinity occurs in groundwater'' in some near-coastal boreholes, most likely as a result of mixing with seawater.
* ''Most trace elements have low concentrations'', in accordance with the neutral pH groundwater conditions. Concentrations of arsenic are relatively high in some groundwaters (up to 8.8 μg/l), though none exceeds the EC maximum permissible value for drinking water of 10 μg/l. Concentrations of uranium reach up to 15.4 μg/l, with the highest concentration just exceeding the WHO provisional guideline value for drinking water of 15 μg/l. Two other exceedances above maximum permissible values for drinking were observed, for nitrite (highest concentration 0.194 mg/l.) and fluoride (highest concentration 3.7 mg/l.).
* ''The chemistry and residence time'' indicators (CFC and stable isotopes) indicate that the groundwaters are largely of young age, being mostly recharged within the last 40 years, with mixing throughout the top 100 m of the aqufier. The young age of the groundwaters means they are vulnerable to contamination.
* ''The most significant groundwater-quality problems'' identified by this survey are:
# The widespread presence of elevated nitrate concentrations in groundwater, which is strongly linked to agricultural activity;
# Elevated phosphate concentrations, which may affect the quality of surface water when discharged to rivers as baseflow.
# The presence of saline water in some near-coastal boreholes, indicating localised saline intrusion. It is not clear to what degree the saline intrusion is natural and to what degree it has been enhanced by over-pumping.
===Data===
* [[Media:AppinGroup.jpg|Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (1 of 2)]]
* [[Media:AppinGroup.jpg|Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (2 of 2)]]
* [[Media:AppinGroup.jpg|Strathmore groundwater — Piper diagram of the major ion chemistry]]
* [[Media:AppinGroup.jpg|Ca, Mg and HCO3 and Cl, SO4, NO3-N — Maps illustrating spatial variation in the concentration]]
* [[Media:AppinGroup.jpg|Na, K and P and F, Fe and Mn — Maps illustrating spatial variation in the concentration]]

==Baseline report===
Ó Dochartaigh, B. É., Smedley, P., MacDonald, A. M. and Darling, W. G. (2004) Baseline Scotland: the Lower Devonian aquifer of Strathmore. Commissioned Report, CR/06/250N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Strathmore

2026-06-24T09:24:02Z

Ajhil: /* Baseline data */

{{Underconstruction}}
===Strathmore===
A total of 48 groundwater samples, collected from boreholes, springs and shallow wells, were used to interpret the chemistry of groundwater in the high productivity Devonian sedimentary aquifer.

[[Image:Samples_Strathmore.jpg|frameless|center|500px|]]

<center>'''Baseline samples in Strathmore; the backdrop is the 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/10299/ Baseline Scotland: the Lower Devonian aquifer of Strathmore] report.

===Baseline data===
'''Main findings''' 
The collection and interpretation of new groundwater chemistry data for the Strathmore area has led to the following conclusions:

* ''The groundwaters of the Devonian aquifer in Strathmore are mainly weakly mineralised'', with TDS concentrations mostly less than 400 mg/l. Groundwaters have near-neutral to slightly alkaline pH values and are for the most part oxygenated, with detectable dissolved oxygen and high redox potentials. As a result, dissolved iron, manganese and ammonium (NH4-N) concentrations are usually low. Water from shallow boreholes and springs is often undersaturated with calcite, but in deeper boreholes, reaction with carbonate minerals in the aquifer is more usual and most of these are saturated with respect to calcite.
* ''Nitrate concentrations'' are often high and nearly one third of the samples exceeded the EC drinking water limit for nitrate of 11.4 mg/l.1 as NO3-N. Under the oxidising conditions, nitrate is a stable solute species across the aquifer and is found at depths in excess of 100 m.
* ''Concentrations of phosphorous'' in groundwater across the aquifer are typically less than 0.1 mg/l. Given the importance of P in controlling eutrophication in surface water, these concentrations in groundwater may be significant.
* ''Increased salinity occurs in groundwater'' in some near-coastal boreholes, most likely as a result of mixing with seawater.
* ''Most trace elements have low concentrations'', in accordance with the neutral pH groundwater conditions. Concentrations of arsenic are relatively high in some groundwaters (up to 8.8 μg/l), though none exceeds the EC maximum permissible value for drinking water of 10 μg/l. Concentrations of uranium reach up to 15.4 μg/l, with the highest concentration just exceeding the WHO provisional guideline value for drinking water of 15 μg/l. Two other exceedances above maximum permissible values for drinking were observed, for nitrite (highest concentration 0.194 mg/l.) and fluoride (highest concentration 3.7 mg/l.).
* ''The chemistry and residence time'' indicators (CFC and stable isotopes) indicate that the groundwaters are largely of young age, being mostly recharged within the last 40 years, with mixing throughout the top 100 m of the aqufier. The young age of the groundwaters means they are vulnerable to contamination.
* ''The most significant groundwater-quality problems'' identified by this survey are:
# The widespread presence of elevated nitrate concentrations in groundwater, which is strongly linked to agricultural activity;
# Elevated phosphate concentrations, which may affect the quality of surface water when discharged to rivers as baseflow.
# The presence of saline water in some near-coastal boreholes, indicating localised saline intrusion. It is not clear to what degree the saline intrusion is natural and to what degree it has been enhanced by over-pumping.
===Data===
Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (1 of 2)
Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (2 of 2)
Strathmore groundwater — Piper diagram of the major ion chemistry
Ca, Mg and HCO3 and Cl, SO4, NO3-N — Maps illustrating spatial variation in the concentration
Na, K and P and F, Fe and Mn — Maps illustrating spatial variation in the concentration
Baseline report
Ó Dochartaigh, B. É., Smedley, P., MacDonald, A. M. and Darling, W. G. (2004) Baseline Scotland: the Lower Devonian aquifer of Strathmore. Commissioned Report, CR/06/250N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Strathmore

2026-06-24T09:18:49Z

Ajhil: /* Strathmore */

{{Underconstruction}}
===Strathmore===
A total of 48 groundwater samples, collected from boreholes, springs and shallow wells, were used to interpret the chemistry of groundwater in the high productivity Devonian sedimentary aquifer.

[[Image:Samples_Strathmore.jpg|frameless|center|500px|]]

<center>'''Baseline samples in Strathmore; the backdrop is the 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/10299/ Baseline Scotland: the Lower Devonian aquifer of Strathmore] report.

===Baseline data===
'''Main findings
'''The collection and interpretation of new groundwater chemistry data for the Strathmore area has led to the following conclusions:

The groundwaters of the Devonian aquifer in Strathmore are mainly weakly mineralised, with TDS concentrations mostly less than 400 mg/l. Groundwaters have near-neutral to slightly alkaline pH values and are for the most part oxygenated, with detectable dissolved oxygen and high redox potentials. As a result, dissolved iron, manganese and ammonium (NH4-N) concentrations are usually low. Water from shallow boreholes and springs is often undersaturated with calcite, but in deeper boreholes, reaction with carbonate minerals in the aquifer is more usual and most of these are saturated with respect to calcite.
Nitrate concentrations are often high and nearly one third of the samples exceeded the EC drinking water limit for nitrate of 11.4 mg/l.1 as NO3-N. Under the oxidising conditions, nitrate is a stable solute species across the aquifer and is found at depths in excess of 100 m.
Concentrations of phosphorous in groundwater across the aquifer are typically less than 0.1 mg/l.. Given the importance of P in controlling eutrophication in surface water, these concentrations in groundwater may be significant.
Increased salinity occurs in groundwater in some near-coastal boreholes, most likely as a result of mixing with seawater.
Most trace elements have low concentrations, in accordance with the neutral pH groundwater conditions. Concentrations of arsenic are relatively high in some groundwaters (up to 8.8 μg/l), though none exceeds the EC maximum permissible value for drinking water of 10 μg/l. Concentrations of uranium reach up to 15.4 μg/l, with the highest concentration just exceeding the WHO provisional guideline value for drinking water of 15 μg/l. Two other exceedances above maximum permissible values for drinking were observed, for nitrite (highest concentration 0.194 mg/l.) and fluoride (highest concentration 3.7 mg/l.).
The chemistry and residence time indicators (CFC and stable isotopes) indicate that the groundwaters are largely of young age, being mostly recharged within the last 40 years, with mixing throughout the top 100 m of the aqufier. The young age of the groundwaters means they are vulnerable to contamination.
The most significant groundwater-quality problems identified by this survey are:
The widespread presence of elevated nitrate concentrations in groundwater, which is strongly linked to agricultural activity;
Elevated phosphate concentrations, which may affect the quality of surface water when discharged to rivers as baseflow.
The presence of saline water in some near-coastal boreholes, indicating localised saline intrusion. It is not clear to what degree the saline intrusion is natural and to what degree it has been enhanced by over-pumping.
Data
Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (1 of 2)
Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (2 of 2)
Strathmore groundwater — Piper diagram of the major ion chemistry
Ca, Mg and HCO3 and Cl, SO4, NO3-N — Maps illustrating spatial variation in the concentration
Na, K and P and F, Fe and Mn — Maps illustrating spatial variation in the concentration
Baseline report
Ó Dochartaigh, B. É., Smedley, P., MacDonald, A. M. and Darling, W. G. (2004) Baseline Scotland: the Lower Devonian aquifer of Strathmore. Commissioned Report, CR/06/250N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Strathmore

2026-06-24T09:18:32Z

Ajhil: /* Strathmore */

{{Underconstruction}}
===Strathmore===
A total of 48 groundwater samples, collected from boreholes, springs and shallow wells, were used to interpret the chemistry of groundwater in the high productivity Devonian sedimentary aquifer.

[[Image:Samples_Strathmore.jpg|frameless|center|500px|]]

<center>'''Baseline samples in Strathmore; the backdrop is the 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/10299/ Baseline Scotland: the Lower Devonian aquifer of Strathmore] report.

===Baseline data===
'''Main findings
'''The collection and interpretation of new groundwater chemistry data for the Strathmore area has led to the following conclusions:

The groundwaters of the Devonian aquifer in Strathmore are mainly weakly mineralised, with TDS concentrations mostly less than 400 mg/l. Groundwaters have near-neutral to slightly alkaline pH values and are for the most part oxygenated, with detectable dissolved oxygen and high redox potentials. As a result, dissolved iron, manganese and ammonium (NH4-N) concentrations are usually low. Water from shallow boreholes and springs is often undersaturated with calcite, but in deeper boreholes, reaction with carbonate minerals in the aquifer is more usual and most of these are saturated with respect to calcite.
Nitrate concentrations are often high and nearly one third of the samples exceeded the EC drinking water limit for nitrate of 11.4 mg/l.1 as NO3-N. Under the oxidising conditions, nitrate is a stable solute species across the aquifer and is found at depths in excess of 100 m.
Concentrations of phosphorous in groundwater across the aquifer are typically less than 0.1 mg/l.. Given the importance of P in controlling eutrophication in surface water, these concentrations in groundwater may be significant.
Increased salinity occurs in groundwater in some near-coastal boreholes, most likely as a result of mixing with seawater.
Most trace elements have low concentrations, in accordance with the neutral pH groundwater conditions. Concentrations of arsenic are relatively high in some groundwaters (up to 8.8 μg/l), though none exceeds the EC maximum permissible value for drinking water of 10 μg/l. Concentrations of uranium reach up to 15.4 μg/l, with the highest concentration just exceeding the WHO provisional guideline value for drinking water of 15 μg/l. Two other exceedances above maximum permissible values for drinking were observed, for nitrite (highest concentration 0.194 mg/l.) and fluoride (highest concentration 3.7 mg/l.).
The chemistry and residence time indicators (CFC and stable isotopes) indicate that the groundwaters are largely of young age, being mostly recharged within the last 40 years, with mixing throughout the top 100 m of the aqufier. The young age of the groundwaters means they are vulnerable to contamination.
The most significant groundwater-quality problems identified by this survey are:
The widespread presence of elevated nitrate concentrations in groundwater, which is strongly linked to agricultural activity;
Elevated phosphate concentrations, which may affect the quality of surface water when discharged to rivers as baseflow.
The presence of saline water in some near-coastal boreholes, indicating localised saline intrusion. It is not clear to what degree the saline intrusion is natural and to what degree it has been enhanced by over-pumping.
Data
Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (1 of 2)
Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (2 of 2)
Strathmore groundwater — Piper diagram of the major ion chemistry
Ca, Mg and HCO3 and Cl, SO4, NO3-N — Maps illustrating spatial variation in the concentration
Na, K and P and F, Fe and Mn — Maps illustrating spatial variation in the concentration
Baseline report
Ó Dochartaigh, B. É., Smedley, P., MacDonald, A. M. and Darling, W. G. (2004) Baseline Scotland: the Lower Devonian aquifer of Strathmore. Commissioned Report, CR/06/250N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

File:Samples Strathmore.jpg

2026-06-24T09:16:46Z

Ajhil:

Strathmore

2026-06-24T09:16:24Z

Ajhil:

{{Underconstruction}}
===Strathmore===
A total of 48 groundwater samples, collected from boreholes, springs and shallow wells, were used to interpret the chemistry of groundwater in the high productivity Devonian sedimentary aquifer.

[[Image:Samples_Strathmore.jpg|frameless|center|500px|]]

<center>'''Baseline samples in Strathmore; the backdrop is the 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the Baseline Scotland: the Lower Devonian aquifer of Strathmore report.

Baseline data
Main findings
The collection and interpretation of new groundwater chemistry data for the Strathmore area has led to the following conclusions:

The groundwaters of the Devonian aquifer in Strathmore are mainly weakly mineralised, with TDS concentrations mostly less than 400 mg/l. Groundwaters have near-neutral to slightly alkaline pH values and are for the most part oxygenated, with detectable dissolved oxygen and high redox potentials. As a result, dissolved iron, manganese and ammonium (NH4-N) concentrations are usually low. Water from shallow boreholes and springs is often undersaturated with calcite, but in deeper boreholes, reaction with carbonate minerals in the aquifer is more usual and most of these are saturated with respect to calcite.
Nitrate concentrations are often high and nearly one third of the samples exceeded the EC drinking water limit for nitrate of 11.4 mg/l.1 as NO3-N. Under the oxidising conditions, nitrate is a stable solute species across the aquifer and is found at depths in excess of 100 m.
Concentrations of phosphorous in groundwater across the aquifer are typically less than 0.1 mg/l.. Given the importance of P in controlling eutrophication in surface water, these concentrations in groundwater may be significant.
Increased salinity occurs in groundwater in some near-coastal boreholes, most likely as a result of mixing with seawater.
Most trace elements have low concentrations, in accordance with the neutral pH groundwater conditions. Concentrations of arsenic are relatively high in some groundwaters (up to 8.8 μg/l), though none exceeds the EC maximum permissible value for drinking water of 10 μg/l. Concentrations of uranium reach up to 15.4 μg/l, with the highest concentration just exceeding the WHO provisional guideline value for drinking water of 15 μg/l. Two other exceedances above maximum permissible values for drinking were observed, for nitrite (highest concentration 0.194 mg/l.) and fluoride (highest concentration 3.7 mg/l.).
The chemistry and residence time indicators (CFC and stable isotopes) indicate that the groundwaters are largely of young age, being mostly recharged within the last 40 years, with mixing throughout the top 100 m of the aqufier. The young age of the groundwaters means they are vulnerable to contamination.
The most significant groundwater-quality problems identified by this survey are:
The widespread presence of elevated nitrate concentrations in groundwater, which is strongly linked to agricultural activity;
Elevated phosphate concentrations, which may affect the quality of surface water when discharged to rivers as baseflow.
The presence of saline water in some near-coastal boreholes, indicating localised saline intrusion. It is not clear to what degree the saline intrusion is natural and to what degree it has been enhanced by over-pumping.
Data
Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (1 of 2)
Devonian Strathmore aquifer — Summary statistics of groundwater chemistry (2 of 2)
Strathmore groundwater — Piper diagram of the major ion chemistry
Ca, Mg and HCO3 and Cl, SO4, NO3-N — Maps illustrating spatial variation in the concentration
Na, K and P and F, Fe and Mn — Maps illustrating spatial variation in the concentration
Baseline report
Ó Dochartaigh, B. É., Smedley, P., MacDonald, A. M. and Darling, W. G. (2004) Baseline Scotland: the Lower Devonian aquifer of Strathmore. Commissioned Report, CR/06/250N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Southern Scotland

2026-06-24T09:14:10Z

Ajhil: /* Baseline report */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/9164/ Baseline Scotland: groundwater chemistry of southern Scotland] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

* ''Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5)''. Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
* ''Bicarbonate alkalinity: HCO3'' is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
* ''Cl and SO4 concentrations'' are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
* ''Concentrations of the major cations'' reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
* ''Most of the groundwaters in the study area are oxidising'', with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
* ''Nitrate concentrations'' are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (>5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
* ''Concentrations of phosphorous'' in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30–70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.

===Interpretations in terms of groundwater flow in southern Scotland===
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

===Data===
'''Tables of summary statistics''' 
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

* [[Media:Summarytable_silurian.jpg|Silurian — Table of summary statistics]]
* [[Media:Summarytable_ordovician.jpg|Ordovician — Table of summary statistics]]
* [[Media:Summarytable_devonian.jpg|Devonian — Table of summary statistics]]
* [[Media:Summarytable_carboniferous.jpg|Carboniferous — Table of summary statistics]]
* [[Media:Piper_individual3.jpg|Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.]]

===Maps of regional variation in selected ion concentrations===
* [[Media:SSmaps.jpg|pH and HCO3 — Maps illustrating spatial variation in the concentration]]
* [[Media:SSmap2.jpg|Na and K — Maps illustrating spatial variation in the concentration]]
* [[Media:SSmap3.jpg|Mg and Ca — Maps illustrating spatial variation in the concentration]]
* [[Media:SSmap4.jpg|NO3-N and Fe — Maps illustrating spatial variation in the concentration]]
* [[Media:SSmap5.jpg|Mn and F — Maps illustrating spatial variation in the concentration]]

===Baseline report===
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. [https://nora.nerc.ac.uk/id/eprint/9164/ Baseline Scotland: groundwater chemistry of southern Scotland]. Commissioned Report, OR/08/062N. British Geological Survey.
[[category:Groundwater and shale gas]]

File:SSmap5.jpg

2026-06-24T09:12:53Z

Ajhil:

File:SSmap4.jpg

2026-06-24T09:12:27Z

Ajhil:

File:SSmap3.jpg

2026-06-24T09:12:03Z

Ajhil:

File:SSmap2.jpg

2026-06-24T09:11:19Z

Ajhil:

File:SSmaps.jpg

2026-06-24T09:10:47Z

Ajhil:

Southern Scotland

2026-06-24T09:10:20Z

Ajhil: /* Maps of regional variation in selected ion concentrations */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/9164/ Baseline Scotland: groundwater chemistry of southern Scotland] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

* ''Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5)''. Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
* ''Bicarbonate alkalinity: HCO3'' is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
* ''Cl and SO4 concentrations'' are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
* ''Concentrations of the major cations'' reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
* ''Most of the groundwaters in the study area are oxidising'', with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
* ''Nitrate concentrations'' are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (>5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
* ''Concentrations of phosphorous'' in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30–70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.

===Interpretations in terms of groundwater flow in southern Scotland===
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

===Data===
'''Tables of summary statistics''' 
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

* [[Media:Summarytable_silurian.jpg|Silurian — Table of summary statistics]]
* [[Media:Summarytable_ordovician.jpg|Ordovician — Table of summary statistics]]
* [[Media:Summarytable_devonian.jpg|Devonian — Table of summary statistics]]
* [[Media:Summarytable_carboniferous.jpg|Carboniferous — Table of summary statistics]]
* [[Media:Piper_individual3.jpg|Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.]]

===Maps of regional variation in selected ion concentrations===
* [[Media:SSmaps.jpg|pH and HCO3 — Maps illustrating spatial variation in the concentration]]
* [[Media:SSmap2.jpg|Na and K — Maps illustrating spatial variation in the concentration]]
* [[Media:SSmap3.jpg|Mg and Ca — Maps illustrating spatial variation in the concentration]]
* [[Media:SSmap4.jpg|NO3-N and Fe — Maps illustrating spatial variation in the concentration]]
* [[Media:SSmap5.jpg|Mn and F — Maps illustrating spatial variation in the concentration]]

===Baseline report===
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

File:Piper individual3.jpg

2026-06-24T09:06:34Z

Ajhil:

File:Summarytable carboniferous.jpg

2026-06-24T09:05:47Z

Ajhil:

File:Summarytable devonian.jpg

2026-06-24T09:05:22Z

Ajhil:

File:Summarytable ordovician.jpg

2026-06-24T09:04:53Z

Ajhil:

File:Summarytable silurian.jpg

2026-06-24T09:04:04Z

Ajhil:

Southern Scotland

2026-06-24T09:03:33Z

Ajhil: /* Data */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/9164/ Baseline Scotland: groundwater chemistry of southern Scotland] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

* ''Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5)''. Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
* ''Bicarbonate alkalinity: HCO3'' is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
* ''Cl and SO4 concentrations'' are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
* ''Concentrations of the major cations'' reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
* ''Most of the groundwaters in the study area are oxidising'', with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
* ''Nitrate concentrations'' are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (>5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
* ''Concentrations of phosphorous'' in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30–70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.

===Interpretations in terms of groundwater flow in southern Scotland===
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

===Data===
'''Tables of summary statistics''' 
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

* [[Media:Summarytable_silurian.jpg|Silurian — Table of summary statistics]]
* [[Media:Summarytable_ordovician.jpg|Ordovician — Table of summary statistics]]
* [[Media:Summarytable_devonian.jpg|Devonian — Table of summary statistics]]
* [[Media:Summarytable_carboniferous.jpg|Carboniferous — Table of summary statistics]]
* [[Media:Piper_individual3.jpg|Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.]]

===Maps of regional variation in selected ion concentrations===
pH and HCO3 — Maps illustrating spatial variation in the concentration
Na and K — Maps illustrating spatial variation in the concentration
Mg and Ca — Maps illustrating spatial variation in the concentration
NO3-N and Fe — Maps illustrating spatial variation in the concentration
Mn and F — Maps illustrating spatial variation in the concentration
Baseline report
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Southern Scotland

2026-06-24T08:59:38Z

Ajhil: /* Interpretations in terms of groundwater flow in southern Scotland */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/9164/ Baseline Scotland: groundwater chemistry of southern Scotland] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

* ''Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5)''. Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
* ''Bicarbonate alkalinity: HCO3'' is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
* ''Cl and SO4 concentrations'' are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
* ''Concentrations of the major cations'' reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
* ''Most of the groundwaters in the study area are oxidising'', with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
* ''Nitrate concentrations'' are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (>5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
* ''Concentrations of phosphorous'' in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30–70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.

===Interpretations in terms of groundwater flow in southern Scotland===
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

===Data===
'''Tables of summary statistics''' 
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

Silurian — Table of summary statistics
Ordovician — Table of summary statistics
Devonian — Table of summary statistics
Carboniferous — Table of summary statistics
Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.
Maps of regional variation in selected ion concentrations
pH and HCO3 — Maps illustrating spatial variation in the concentration
Na and K — Maps illustrating spatial variation in the concentration
Mg and Ca — Maps illustrating spatial variation in the concentration
NO3-N and Fe — Maps illustrating spatial variation in the concentration
Mn and F — Maps illustrating spatial variation in the concentration
Baseline report
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Southern Scotland

2026-06-24T08:58:20Z

Ajhil: /* Main findings */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/9164/ Baseline Scotland: groundwater chemistry of southern Scotland] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

* ''Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5)''. Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
* ''Bicarbonate alkalinity: HCO3'' is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
* ''Cl and SO4 concentrations'' are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
* ''Concentrations of the major cations'' reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
* ''Most of the groundwaters in the study area are oxidising'', with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
* ''Nitrate concentrations'' are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (>5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
* ''Concentrations of phosphorous'' in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30–70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.

===Interpretations in terms of groundwater flow in southern Scotland===
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

Data
Tables of summary statistics
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

Silurian — Table of summary statistics
Ordovician — Table of summary statistics
Devonian — Table of summary statistics
Carboniferous — Table of summary statistics
Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.
Maps of regional variation in selected ion concentrations
pH and HCO3 — Maps illustrating spatial variation in the concentration
Na and K — Maps illustrating spatial variation in the concentration
Mg and Ca — Maps illustrating spatial variation in the concentration
NO3-N and Fe — Maps illustrating spatial variation in the concentration
Mn and F — Maps illustrating spatial variation in the concentration
Baseline report
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Southern Scotland

2026-06-24T08:57:41Z

Ajhil: /* Main findings */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/9164/ Baseline Scotland: groundwater chemistry of southern Scotland] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

* ''Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5)''. Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
* ''Bicarbonate alkalinity: HCO3'' is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
* ''Cl and SO4 concentrations'' are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
* ''Concentrations of the major cations'' reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
* ''Most of the groundwaters in the study area are oxidising'', with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
* ''Nitrate concentrations'' are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (>5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
* ''Concentrations of phosphorous'' in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30-70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.

===Interpretations in terms of groundwater flow in southern Scotland===
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

Data
Tables of summary statistics
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

Silurian — Table of summary statistics
Ordovician — Table of summary statistics
Devonian — Table of summary statistics
Carboniferous — Table of summary statistics
Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.
Maps of regional variation in selected ion concentrations
pH and HCO3 — Maps illustrating spatial variation in the concentration
Na and K — Maps illustrating spatial variation in the concentration
Mg and Ca — Maps illustrating spatial variation in the concentration
NO3-N and Fe — Maps illustrating spatial variation in the concentration
Mn and F — Maps illustrating spatial variation in the concentration
Baseline report
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Southern Scotland

2026-06-24T08:56:31Z

Ajhil: /* Southern Scotland */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/9164/ Baseline Scotland: groundwater chemistry of southern Scotland] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

* ''Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5)''. Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
* ''Bicarbonate alkalinity: HCO3'' is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
* ''Cl and SO4 concentrations'' are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
* ''Concentrations of the major cations'' reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
* ''Most of the groundwaters in the study area are oxidising'', with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
* ''Nitrate concentrations'' are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (> 5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
* ''Concentrations of phosphorous'' in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30-70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.
===Interpretations in terms of groundwater flow in southern Scotland===
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

Data
Tables of summary statistics
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

Silurian — Table of summary statistics
Ordovician — Table of summary statistics
Devonian — Table of summary statistics
Carboniferous — Table of summary statistics
Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.
Maps of regional variation in selected ion concentrations
pH and HCO3 — Maps illustrating spatial variation in the concentration
Na and K — Maps illustrating spatial variation in the concentration
Mg and Ca — Maps illustrating spatial variation in the concentration
NO3-N and Fe — Maps illustrating spatial variation in the concentration
Mn and F — Maps illustrating spatial variation in the concentration
Baseline report
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Southern Scotland

2026-06-24T08:52:48Z

Ajhil: /* Southern Scotland */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the [https://nora.nerc.ac.uk/id/eprint/9164/ Baseline Scotland: groundwater chemistry of southern Scotland] report.

Main findings
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5). Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
Bicarbonate alkalinity: HCO3 is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
Cl and SO4 concentrations are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
Concentrations of the major cations reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
Most of the groundwaters in the study area are oxidising, with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
Nitrate concentrations are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (> 5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
Concentrations of phosphorous in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30-70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.
Interpretations in terms of groundwater flow in southern Scotland
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

Data
Tables of summary statistics
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

Silurian — Table of summary statistics
Ordovician — Table of summary statistics
Devonian — Table of summary statistics
Carboniferous — Table of summary statistics
Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.
Maps of regional variation in selected ion concentrations
pH and HCO3 — Maps illustrating spatial variation in the concentration
Na and K — Maps illustrating spatial variation in the concentration
Mg and Ca — Maps illustrating spatial variation in the concentration
NO3-N and Fe — Maps illustrating spatial variation in the concentration
Mn and F — Maps illustrating spatial variation in the concentration
Baseline report
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Southern Scotland

2026-06-24T08:50:31Z

Ajhil: /* Southern Scotland */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the Baseline Scotland: groundwater chemistry of southern Scotland report.

Main findings
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5). Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
Bicarbonate alkalinity: HCO3 is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
Cl and SO4 concentrations are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
Concentrations of the major cations reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
Most of the groundwaters in the study area are oxidising, with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
Nitrate concentrations are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (> 5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
Concentrations of phosphorous in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30-70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.
Interpretations in terms of groundwater flow in southern Scotland
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

Data
Tables of summary statistics
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

Silurian — Table of summary statistics
Ordovician — Table of summary statistics
Devonian — Table of summary statistics
Carboniferous — Table of summary statistics
Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.
Maps of regional variation in selected ion concentrations
pH and HCO3 — Maps illustrating spatial variation in the concentration
Na and K — Maps illustrating spatial variation in the concentration
Mg and Ca — Maps illustrating spatial variation in the concentration
NO3-N and Fe — Maps illustrating spatial variation in the concentration
Mn and F — Maps illustrating spatial variation in the concentration
Baseline report
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

File:Samples southernScotland1.jpg

2026-06-24T08:50:09Z

Ajhil:

Southern Scotland

2026-06-24T08:49:32Z

Ajhil: /* Southern Scotland */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland1.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the Baseline Scotland: groundwater chemistry of southern Scotland report.

Main findings
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5). Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
Bicarbonate alkalinity: HCO3 is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
Cl and SO4 concentrations are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
Concentrations of the major cations reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
Most of the groundwaters in the study area are oxidising, with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
Nitrate concentrations are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (> 5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
Concentrations of phosphorous in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30-70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.
Interpretations in terms of groundwater flow in southern Scotland
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

Data
Tables of summary statistics
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

Silurian — Table of summary statistics
Ordovician — Table of summary statistics
Devonian — Table of summary statistics
Carboniferous — Table of summary statistics
Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.
Maps of regional variation in selected ion concentrations
pH and HCO3 — Maps illustrating spatial variation in the concentration
Na and K — Maps illustrating spatial variation in the concentration
Mg and Ca — Maps illustrating spatial variation in the concentration
NO3-N and Fe — Maps illustrating spatial variation in the concentration
Mn and F — Maps illustrating spatial variation in the concentration
Baseline report
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

File:Samples southernScotland.jpg

2026-06-24T08:48:22Z

Ajhil:

Southern Scotland

2026-06-24T08:47:54Z

Ajhil: /* Southern Scotland */

{{Underconstruction}}
===Southern Scotland===
A total of 78 groundwater sample analyses from the Silurian, Ordovician, Devonian, Carboniferous and igneous aquifers in southern Scotland were interpreted to investigate the groundwater chemistry of these aquifers. The samples were collected between 2002 and 2006. Permian aquifers in southern Scotland were not included in this study; they will be reported on separately.

[[Image:Samples_southernScotland.jpg|frameless|center|500px|]]

<center>'''Baseline samples in southern Scotland against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Download the Baseline Scotland: groundwater chemistry of southern Scotland report.

Main findings
The collection and interpretation of new groundwater chemistry data for southern Scotland has led to the following conclusions:

Most of the groundwater pH values in the region are in the near-neutral range (6.5–8.5). Groundwaters from Ordovician and Silurian rocks tend to have a slightly lower pH than those from Devonian sandstones and Carboniferous sandstones and limestones. Groundwaters from igneous rocks and mineralised Lower Palaeozoic strata are more acidic, with occasional pH values below 6.5.
Bicarbonate alkalinity: HCO3 is in the range 100–250 mg/l for Ordovician and Silurian groundwaters, 200–320 mg/l for Devonian and Carboniferous groundwaters, and <100 mg/l for igneous groundwaters and mineralised springs from the Lower Palaeozoic.
Cl and SO4 concentrations are generally low and reflect inputs from rainfall, with the exception of Carboniferous groundwaters which tend to have highest concentrations of Cl and SO4, possibly reflecting the influence of connate water and sulphide mineralisation within interbedded mudstone.
Concentrations of the major cations reflect a combination of rainfall input, mineral weathering, and anthropogenic inputs derived from the use of fertilisers and liming (or from other sources of pollution). Most notable is an enrichment of K (5–10 mg/l) in groundwaters from Carboniferous sedimentary rocks, probably resulting from feldspar weathering. Ca concentrations broadly reflect the distribution of calcite in rocks. Groundwater from Ordovician, Silurian and mineralised strata and igneous aquifers are undersaturated with respect to calcite, as would be expected from their non-carbonate mineralogy. Groundwater from the Devonian and Carboniferous strata are generally saturated or supersaturated with respect to calcite, indicating the presence of calcite either as a major (Carboniferous limestone) or minor (calcite cement in Devonian sandstones) component.
Most of the groundwaters in the study area are oxidising, with dissolved oxygen concentrations in the range 1–7 mg/l and a redox potential (Eh) greater than 300 mV. However, the mineralised springs are reducing, with sulphate reduction indicated at St Ronan’s Well. Groundwaters from Carboniferous strata in general tend to be slightly less oxidising than those from other aquifers. Apart from these incidences, however, the groundwater redox status does not appear to vary strongly with geology.
Nitrate concentrations are typically low: the median concentration of nitrate in groundwater is less than 5 mg/l NO3-N across the aquifers. Concentrations are related to land use, with groundwaters beneath agricultural land showing higher concentrations than those beneath non-agricultural land. Elevated nitrate concentrations (> 5 mg/l NO3-N) are found outwith the current designated Nitrate Vulnerable Zones (NVZs). The most noticeable are in the west of the study area in Galloway, where high concentrations are associated with improved pasture, and in particular dairy farming.
Concentrations of phosphorous in groundwater can be an important influence on surface water eutrophication if present in baseflow to streams and rivers. Median P concentrations for the aquifer units in southern Scotland tend to fall in the range 30-70 μg/l-P. P concentrations do not show any strong relationship with land use, illustrating the complexity of P geochemistry, and the important role that soil geochemistry plays in the mobilisation of P into groundwater.
Interpretations in terms of groundwater flow in southern Scotland
The hydrochemistry data and information on groundwater residence times help give an insight into groundwater flow in the different aquifers in southern Scotland. The best interpretation of the groundwater flow system within all of these aquifers is that it is largely through fractures, and well mixed in the top 50 metres or so. This is supported by the lack of correlation of nitrate with source depth across the region, and by the relative proportions of CFC and SF6 concentrations, which indicate mixing rather than piston flow models.

There is no evidence of paleaowater in the area, and (where CFC and SF6 have been measured) all samples recorded some proportion of water less than 50 years old. However, groundwater, even in the more fractured less permeable Lower Palaeozoic aquifers, can be resident for several decades.

Groundwater samples in the upland areas of southern Scotland often contain a large element of water that fell as rain on higher ground (as implied by depleted stable isotope data). This suggests connected groundwater systems, or possible in some instances reinfiltration of upland run-off into the groundwater systems.

Data
Tables of summary statistics
The tables below provide a statistical summary of the natural variation in groundwater chemistry in each of the studied aquifers in southern Scotland: Silurian, Ordovician, Devonian and Carboniferous. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time.

The data indicate systematic variations in some solutes with geology. Most noticeable is the saturation and supersaturation of calcite in groundwater from Devonian and Carboniferous aquifers and the lack of calcite in many of the samples from the Silurian and Ordovician aquifers. Another difference is the elevation of sulphate and potassium in groundwaters from the Carboniferous aquifer compared to other waters.

Samples from igneous aquifers also have different groundwater chemistry to the main aquifers, but there are too few samples in this group to draw conclusions about the expected baseline chemistry that are statistically meaningful.

Concentrations in italics in the tables below are below instrumental detection limits and have been estimated using a robust 'regression on order' statistics ('ROS') approach. For further detail on this statistical approach, see the full Southern Scotland Baseline report at the bottom of this page.

Silurian — Table of summary statistics
Ordovician — Table of summary statistics
Devonian — Table of summary statistics
Carboniferous — Table of summary statistics
Piper diagrams illustrate the distribution of groundwater chemistry data for the four main aquifers, and indicate outliers.
Maps of regional variation in selected ion concentrations
pH and HCO3 — Maps illustrating spatial variation in the concentration
Na and K — Maps illustrating spatial variation in the concentration
Mg and Ca — Maps illustrating spatial variation in the concentration
NO3-N and Fe — Maps illustrating spatial variation in the concentration
Mn and F — Maps illustrating spatial variation in the concentration
Baseline report
MacDonald, A M, Ó Dochartaigh, B É, Kinniburgh, D G and Darling, W G. 2008. Baseline Scotland: groundwater chemistry of southern Scotland. Commissioned Report, OR/08/062N. British Geological Survey.
Please contact [https://www.bgs.ac.uk/about-bgs/contact-us/ BGS Enquiries] for more information.
[[category:Groundwater and shale gas]]

Moray Firth

2026-06-24T08:46:58Z

Ajhil: /* Maps of regional variation in selected ion concentrations */

{{Underconstruction}}
===Moray Firth===
Moray Firth
Coverage of baseline sampling in the Moray Firth against a simplified 1:625 000 scale geology map.
Coverage of baseline sampling in the Moray Firth against a simplified 1:625 000 scale geology map.
A total of 39 groundwater samples have been interpreted to investigate the groundwater chemistry of the Old Red Sandstone aquifers in the Moray Firth area. Of these, 17 were collected in 2007 specifically for the Baseline Scotland project. These were augmented with a further 22 samples collected during separate BGS projects since 2001. The sites were chosen so that the data would be representative of groundwater across the Old Red Sandstone aquifers in the area.

[[Image:Samplingpts_Morayshire (1).jpg|frameless|center|500px|]]

<center>'''Coverage of baseline sampling in the Moray Firth against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Three main aquifer units were sampled: the Lower, Middle and Upper Old Red Sandstones in the Moray Firth area.

Download the [https://nora.nerc.ac.uk/id/eprint/10293/ Baseline Scotland: groundwater chemistry of the Old Red Sandstone aquifers of the Moray Firth area] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for the Old Red Sandstone aquifers in the Moray Firth area has led to the following conclusions:

* Groundwater in the Old Red Sandstone aquifers of the Moray Firth is generally moderately mineralised, with a median SEC of 469 μS/cm (interquartile range 341–591 μS/cm). The major ion chemistry appears to be dominated by the dissolution of carbonate cements within the aquifer and overlying deposits, and the variable influence of seawater (either directly as saline intrusion or as aerosols).
* ''Groundwater pH values'' are variable (5.33–8.06), but the median pH value is near-neutral (7.31). In general the pH of the Lower and Middle Old Red Sandstone aquifers is slightly more acidic, usually less than 7.0.
* ''Concentrations of the major cations''. The dominant cation is Ca, with a median concentration of 54.8 mg/L (interquartile range 42.5–74 mg/L). Mg and K concentrations are generally low (median 4.21 and 3.7 mg/L, respectively). The median Na is 20.6 mg/L (interquartile range 12.6–28 mg/L); however, a few samples have been affected by the proximity to the sea and have much higher concentrations (95th percentile 68 mg/L, and maximum concentration 153 mg/L).
* ''Concentrations of the major anions''. The dominant anion is bicarbonate, with a median concentration of 183 mg/L (interquartile range 183–230 mg/L). Around one third of the samples are saturated with respect to calcite. Sulphate concentrations are generally low (median 14.6 mg/L, interquartile range 7.7–36.4 mg/L), although higher concentrations are encountered in samples affected by seawater, and/or possibly by gypsum bands within the aquifer. Chloride concentrations follow broadly the same distribution as Na and have a median of 38.8 mg/L and interquartile range of 19.5–49.5 mg/L; the same few samples show high Cl concentrations as do Na.
* ''There is a large range in redox conditions across the aquifer''. Sub-oxic or mildy reducing groundwaters (where dissolved oxygen (DO) concentrations are <1 mg/L) are prevalent across much of the Upper Old Red Sandstone, and parts of the Middle Old Red Sandstone. These reducing conditions may reflect the presence of low permeability layers (often marine in origin) within the thick superficial deposits overlying the Old Red Sandstone aquifer.
* ''Concentrations of minor and trace elements'' are dominated by the redox conditions. Concentrations of Fe and Mn are relatively high, with median concentrations of 38 and 43 μg/L respectively, and 75th percentile values of 354 and 227 μg/L respectively. Concentrations are highest in the Upper Old Red sandstone outcrop, and parts of the Middle Old Red Sandstone, reflecting the reducing nature of the groundwaters.
* ''Nitrate concentrations'' are variable across the aquifer units, although median concentrations are low (1.45 mg/L TON-N or less in each aquifer). The prevalence of low oxygen conditions in the sampled groundwaters has led to denitrification, which means the relationship between land use and nitrate concentrations is less obvious than for other parts of Scotland (MacDonald et al. 2005). However, there is a clear relationship between nitrate concentrations and the Nitrate Vulnerable Zone (NVZ) that covers much of the study area, with the seven highest groundwater nitrate concentrations, ranging from 5.98 to 22.1 mg/L TON-N, all from samples taken within the NVZ. The highest median concentrations were from samples collected on land known to be used for dairy, pig or poultry farming.
* ''Concentrations of phosphorous'' range from less than detection limit up to 172 μg P/L, with an overall median of 36 μg P/L, which is in the eutrophic range for surface waters. Concentrations are generally low in the western part of the study area, and an observed relationship with the spatial pattern of F suggests that both elements may be in part derived from the dissolution of phosphate minerals, such as apatite, from the aquifer rocks. Concentrations in the eastern part of the study area are generally higher, usually in the mesotropic or eutrophic range for surface waters. The higher values may be related to land use, with P inputs from agricultural activity.

===Interpretations in terms of groundwater flow===
The information on hydrochemistry and groundwater residence times can help give an insight into groundwater flow in the Old Red Sandstone aquifers in the Moray Firth area. There is no evidence of palaeowater in the samples taken from the area; most of the groundwater are interpreted as being less than 50 years old using the SF6 data. The reducing nature of the groundwaters make it difficult to interpret the CFC data (since both CFC-11 and CFC-12 have been reduced) and get a reliable estimate of whether flow is predominantly fracture dominated or piston intergranular flow. Two samples that were not reducing appear to show piston flow; however, groundwater chemistry (in particularly nitrate) show no significant depth correlations, implying that groundwater is well mixed. A possible explanation is that piston flow occurs in the thick overlying superficial deposits, but within the sandstone fracture flow may dominate.

Carbon isotope evidence indicates the significant role of the nature of the superficial cover in impacting the groundwater chemistry, showing differences between groundwaters recharged through glaciofluvial deposits, which are likely to derive bicarbonate from silicate hydrolysis, and those recharged through marine or beach deposits, in which bicarbonate is likely to derive from dissolution of shell carbonate.

===Data===
'''Summary statistics''' 
The table and plot below provide a statistical summary of the natural variation in groundwater chemistry in the Old Red Sandstones aquifers across the Moray Firth area. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time, with the exception of NO3-N and P, where the influence of anthropogenic activity is likely to have distorted baseline conditions throughout much of the area.

* [[Media:LowerOldRedSST.jpg|Lower Old Red Sandstone – Table of summary statistics]]
* [[Media:MiddleOldRedSST.jpg|Middle Old Red Sandstone – Table of summary statistics]]
* [[Media:UpperOldRedSST.jpg|Upper Old Red Sandstone – Table of summary statistics]]
* [[Media:piperplot (1).jpg|Piper diagrams illustrate the distribution of groundwater chemistry data for all Old Red Sandstone aquifers]]

===Lower Old Red Sandstone===
The four Lower Old Red Sandstone groundwater samples showed a range in cation dominance from Ca to Na-K. All but one are dominated by HCO3 anions, with the remaining sample strongly dominated by Cl. Dissolved oxygen and redox (Eh) values are only available for two of the samples, which were oxic. Three of the four samples had below-neutral pH values, and the median was 6.34, lower than the median for the whole Old Red Sandstone dataset. Concentrations of most major ions are lower on average than in Middle and Upper Old Red Sandstone groundwaters, except Mg which is similar. Relatively low Ca concentrations and pH values probably result from a lack of carbonate minerals in the aquifer or overlying superficial deposits, which is also reflected in the lower calcite saturation values for these groundwaters (all but one of the samples was strongly undersaturated with respect to calcite). Iron concentrations are typically low, while manganese concentrations show a larger range, with a low media value.

===Middle Old Red Sandstone===
Groundwaters from the Middle Old Red Sandstone aquifer show an overall cationic dominance by Ca, but a relatively wide spread, trending towards no dominant cation. Their anionic distribution is more restricted, strongly dominated by HCO-3, apart from a single Cl-dominated water. They show very little SO4 influence. Most of the samples are undersaturated with respect to calcite, but less strongly so than the Lower Old Red Sandstone waters.

Dissolved oxygen and Eh measurements are available for only seven of the fourteen Middle Old Red Sandstone samples, of which four are oxic and three are anoxic. The groundwaters have a higher median pH than the Lower Old Red Sandstone waters, and the highest median HCO3 concentration of the three aquifers. SEC and median Ca, Na, K and Cl concentrations are in between the average values for the Lower and the Upper Old Red Sandstone groundwaters. Concentrations of SO4 are, as for the Lower Old Red Sandstone, relatively low, while magnesium concentrations are comparable to the other two aquifers.

[[Manganese (Mn) in Scottish Groundwater | Iron and Mn concentrations]] are highly variable, from low (less than the detection limit for Fe) to high, although both show low median concentrations. The main control on the presence of high Fe and Mn is likely to be the presence of anoxic conditions within the aquifer [https://nora.nerc.ac.uk/id/eprint/9665/ (Hominik et al. 2010)].

===Upper Old Red Sandstone===
Groundwaters from the Upper Old Red Sandstone aquifer typically show very similar cation distribution, dominated by Ca in all but one case, and closely grouped. They show a wider anionic range, from HCO3 towards Cl and SO4. Most of the samples for which DO and Eh measurements are available are anoxic; only three of fourteen samples showed clearly oxic conditions. The groundwaters have the highest median pH value of the three aquifers, and a slightly lower median HCO3 concentration than the Middle Old Red Sandstone waters. The median SEC value and median concentrations of all of the major ions except Mg are also the highest of the three aquifers. SO4 concentrations in particular are noticeably higher than the other two aquifers. Iron and Mn concentrations are also highly variable, from low (less than the detection limit for Fe) to very high. The median Fe concentration is not especially high, but the median Mn concentration is more than twice the drinking water limit. The high concentrations of both of these parameters are linked to the prevalence of anoxic conditions across much of the aquifer [https://nora.nerc.ac.uk/id/eprint/9665/ (Hominik et al. 2010)].

===Maps of regional variation in selected ion concentrations===

* [[Media:pH_HCO3 (2).jpg|pH and HCO3 — Maps illustrating spatial variation in the concentration]]
* [[Media:Na_K (2).jpg|Na and K — Maps illustrating spatial variation in the concentration]]
* [[Media:Ca_Mg (2).jpg|Ca and Mg — Maps illustrating spatial variation in the concentration]]
* [[Media:Cl_SO4 (1).jpg|Cl and SO4 — Maps illustrating spatial variation in the concentration]]
* [[Media:TON_Fe.jpg|TON and Fe — Maps illustrating spatial variation in the concentration]]
* [[Media:Mn_F2.jpg|Mn and F — Maps illustrating spatial variation in the concentration]]

===Reports===
Ó Dochartaigh, B É, Smedley, P L, MacDonald, A M, and Darling, W G. 2010. [https://nora.nerc.ac.uk/id/eprint/10293/ Baseline Scotland: groundwater chemistry of the Old Red Sandstone aquifers of the Moray Firth area]. British Geological Survey Open Report, OR/10/031.

MacDonald, A M, Robins, N S, Ball, D F and Ó Dochartaigh, B É. 2005. [https://nora.nerc.ac.uk/id/eprint/12230/ An overview of groundwater in Scotland]. Scottish Journal of Geology, 41; 1, 3–11.
[[category:Groundwater and shale gas]]

Moray Firth

2026-06-24T08:44:47Z

Ajhil: /* Maps of regional variation in selected ion concentrations */

{{Underconstruction}}
===Moray Firth===
Moray Firth
Coverage of baseline sampling in the Moray Firth against a simplified 1:625 000 scale geology map.
Coverage of baseline sampling in the Moray Firth against a simplified 1:625 000 scale geology map.
A total of 39 groundwater samples have been interpreted to investigate the groundwater chemistry of the Old Red Sandstone aquifers in the Moray Firth area. Of these, 17 were collected in 2007 specifically for the Baseline Scotland project. These were augmented with a further 22 samples collected during separate BGS projects since 2001. The sites were chosen so that the data would be representative of groundwater across the Old Red Sandstone aquifers in the area.

[[Image:Samplingpts_Morayshire (1).jpg|frameless|center|500px|]]

<center>'''Coverage of baseline sampling in the Moray Firth against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Three main aquifer units were sampled: the Lower, Middle and Upper Old Red Sandstones in the Moray Firth area.

Download the [https://nora.nerc.ac.uk/id/eprint/10293/ Baseline Scotland: groundwater chemistry of the Old Red Sandstone aquifers of the Moray Firth area] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for the Old Red Sandstone aquifers in the Moray Firth area has led to the following conclusions:

* Groundwater in the Old Red Sandstone aquifers of the Moray Firth is generally moderately mineralised, with a median SEC of 469 μS/cm (interquartile range 341–591 μS/cm). The major ion chemistry appears to be dominated by the dissolution of carbonate cements within the aquifer and overlying deposits, and the variable influence of seawater (either directly as saline intrusion or as aerosols).
* ''Groundwater pH values'' are variable (5.33–8.06), but the median pH value is near-neutral (7.31). In general the pH of the Lower and Middle Old Red Sandstone aquifers is slightly more acidic, usually less than 7.0.
* ''Concentrations of the major cations''. The dominant cation is Ca, with a median concentration of 54.8 mg/L (interquartile range 42.5–74 mg/L). Mg and K concentrations are generally low (median 4.21 and 3.7 mg/L, respectively). The median Na is 20.6 mg/L (interquartile range 12.6–28 mg/L); however, a few samples have been affected by the proximity to the sea and have much higher concentrations (95th percentile 68 mg/L, and maximum concentration 153 mg/L).
* ''Concentrations of the major anions''. The dominant anion is bicarbonate, with a median concentration of 183 mg/L (interquartile range 183–230 mg/L). Around one third of the samples are saturated with respect to calcite. Sulphate concentrations are generally low (median 14.6 mg/L, interquartile range 7.7–36.4 mg/L), although higher concentrations are encountered in samples affected by seawater, and/or possibly by gypsum bands within the aquifer. Chloride concentrations follow broadly the same distribution as Na and have a median of 38.8 mg/L and interquartile range of 19.5–49.5 mg/L; the same few samples show high Cl concentrations as do Na.
* ''There is a large range in redox conditions across the aquifer''. Sub-oxic or mildy reducing groundwaters (where dissolved oxygen (DO) concentrations are <1 mg/L) are prevalent across much of the Upper Old Red Sandstone, and parts of the Middle Old Red Sandstone. These reducing conditions may reflect the presence of low permeability layers (often marine in origin) within the thick superficial deposits overlying the Old Red Sandstone aquifer.
* ''Concentrations of minor and trace elements'' are dominated by the redox conditions. Concentrations of Fe and Mn are relatively high, with median concentrations of 38 and 43 μg/L respectively, and 75th percentile values of 354 and 227 μg/L respectively. Concentrations are highest in the Upper Old Red sandstone outcrop, and parts of the Middle Old Red Sandstone, reflecting the reducing nature of the groundwaters.
* ''Nitrate concentrations'' are variable across the aquifer units, although median concentrations are low (1.45 mg/L TON-N or less in each aquifer). The prevalence of low oxygen conditions in the sampled groundwaters has led to denitrification, which means the relationship between land use and nitrate concentrations is less obvious than for other parts of Scotland (MacDonald et al. 2005). However, there is a clear relationship between nitrate concentrations and the Nitrate Vulnerable Zone (NVZ) that covers much of the study area, with the seven highest groundwater nitrate concentrations, ranging from 5.98 to 22.1 mg/L TON-N, all from samples taken within the NVZ. The highest median concentrations were from samples collected on land known to be used for dairy, pig or poultry farming.
* ''Concentrations of phosphorous'' range from less than detection limit up to 172 μg P/L, with an overall median of 36 μg P/L, which is in the eutrophic range for surface waters. Concentrations are generally low in the western part of the study area, and an observed relationship with the spatial pattern of F suggests that both elements may be in part derived from the dissolution of phosphate minerals, such as apatite, from the aquifer rocks. Concentrations in the eastern part of the study area are generally higher, usually in the mesotropic or eutrophic range for surface waters. The higher values may be related to land use, with P inputs from agricultural activity.

===Interpretations in terms of groundwater flow===
The information on hydrochemistry and groundwater residence times can help give an insight into groundwater flow in the Old Red Sandstone aquifers in the Moray Firth area. There is no evidence of palaeowater in the samples taken from the area; most of the groundwater are interpreted as being less than 50 years old using the SF6 data. The reducing nature of the groundwaters make it difficult to interpret the CFC data (since both CFC-11 and CFC-12 have been reduced) and get a reliable estimate of whether flow is predominantly fracture dominated or piston intergranular flow. Two samples that were not reducing appear to show piston flow; however, groundwater chemistry (in particularly nitrate) show no significant depth correlations, implying that groundwater is well mixed. A possible explanation is that piston flow occurs in the thick overlying superficial deposits, but within the sandstone fracture flow may dominate.

Carbon isotope evidence indicates the significant role of the nature of the superficial cover in impacting the groundwater chemistry, showing differences between groundwaters recharged through glaciofluvial deposits, which are likely to derive bicarbonate from silicate hydrolysis, and those recharged through marine or beach deposits, in which bicarbonate is likely to derive from dissolution of shell carbonate.

===Data===
'''Summary statistics''' 
The table and plot below provide a statistical summary of the natural variation in groundwater chemistry in the Old Red Sandstones aquifers across the Moray Firth area. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time, with the exception of NO3-N and P, where the influence of anthropogenic activity is likely to have distorted baseline conditions throughout much of the area.

* [[Media:LowerOldRedSST.jpg|Lower Old Red Sandstone – Table of summary statistics]]
* [[Media:MiddleOldRedSST.jpg|Middle Old Red Sandstone – Table of summary statistics]]
* [[Media:UpperOldRedSST.jpg|Upper Old Red Sandstone – Table of summary statistics]]
* [[Media:piperplot (1).jpg|Piper diagrams illustrate the distribution of groundwater chemistry data for all Old Red Sandstone aquifers]]

===Lower Old Red Sandstone===
The four Lower Old Red Sandstone groundwater samples showed a range in cation dominance from Ca to Na-K. All but one are dominated by HCO3 anions, with the remaining sample strongly dominated by Cl. Dissolved oxygen and redox (Eh) values are only available for two of the samples, which were oxic. Three of the four samples had below-neutral pH values, and the median was 6.34, lower than the median for the whole Old Red Sandstone dataset. Concentrations of most major ions are lower on average than in Middle and Upper Old Red Sandstone groundwaters, except Mg which is similar. Relatively low Ca concentrations and pH values probably result from a lack of carbonate minerals in the aquifer or overlying superficial deposits, which is also reflected in the lower calcite saturation values for these groundwaters (all but one of the samples was strongly undersaturated with respect to calcite). Iron concentrations are typically low, while manganese concentrations show a larger range, with a low media value.

===Middle Old Red Sandstone===
Groundwaters from the Middle Old Red Sandstone aquifer show an overall cationic dominance by Ca, but a relatively wide spread, trending towards no dominant cation. Their anionic distribution is more restricted, strongly dominated by HCO-3, apart from a single Cl-dominated water. They show very little SO4 influence. Most of the samples are undersaturated with respect to calcite, but less strongly so than the Lower Old Red Sandstone waters.

Dissolved oxygen and Eh measurements are available for only seven of the fourteen Middle Old Red Sandstone samples, of which four are oxic and three are anoxic. The groundwaters have a higher median pH than the Lower Old Red Sandstone waters, and the highest median HCO3 concentration of the three aquifers. SEC and median Ca, Na, K and Cl concentrations are in between the average values for the Lower and the Upper Old Red Sandstone groundwaters. Concentrations of SO4 are, as for the Lower Old Red Sandstone, relatively low, while magnesium concentrations are comparable to the other two aquifers.

[[Manganese (Mn) in Scottish Groundwater | Iron and Mn concentrations]] are highly variable, from low (less than the detection limit for Fe) to high, although both show low median concentrations. The main control on the presence of high Fe and Mn is likely to be the presence of anoxic conditions within the aquifer [https://nora.nerc.ac.uk/id/eprint/9665/ (Hominik et al. 2010)].

===Upper Old Red Sandstone===
Groundwaters from the Upper Old Red Sandstone aquifer typically show very similar cation distribution, dominated by Ca in all but one case, and closely grouped. They show a wider anionic range, from HCO3 towards Cl and SO4. Most of the samples for which DO and Eh measurements are available are anoxic; only three of fourteen samples showed clearly oxic conditions. The groundwaters have the highest median pH value of the three aquifers, and a slightly lower median HCO3 concentration than the Middle Old Red Sandstone waters. The median SEC value and median concentrations of all of the major ions except Mg are also the highest of the three aquifers. SO4 concentrations in particular are noticeably higher than the other two aquifers. Iron and Mn concentrations are also highly variable, from low (less than the detection limit for Fe) to very high. The median Fe concentration is not especially high, but the median Mn concentration is more than twice the drinking water limit. The high concentrations of both of these parameters are linked to the prevalence of anoxic conditions across much of the aquifer [https://nora.nerc.ac.uk/id/eprint/9665/ (Hominik et al. 2010)].

===Maps of regional variation in selected ion concentrations===

* [[Media:pH_HCO3 (2).jpg|pH and HCO3 — Maps illustrating spatial variation in the concentration]]
* [[Media:Na_K (2).jpg|Na and K — Maps illustrating spatial variation in the concentration]]
* [[Media:Ca_Mg (2).jpg|Ca and Mg — Maps illustrating spatial variation in the concentration]]
* [[Media:Cl_SO4 (1).jpg|Cl and SO4 — Maps illustrating spatial variation in the concentration]]
* [[Media:TON_Fe.jpg|TON and Fe — Maps illustrating spatial variation in the concentration]]
* [[Media:pH_HCO3 (2).jpg|Mn and F — Maps illustrating spatial variation in the concentration]]

===Reports===
Ó Dochartaigh, B É, Smedley, P L, MacDonald, A M, and Darling, W G. 2010. [https://nora.nerc.ac.uk/id/eprint/10293/ Baseline Scotland: groundwater chemistry of the Old Red Sandstone aquifers of the Moray Firth area]. British Geological Survey Open Report, OR/10/031.

MacDonald, A M, Robins, N S, Ball, D F and Ó Dochartaigh, B É. 2005. [https://nora.nerc.ac.uk/id/eprint/12230/ An overview of groundwater in Scotland]. Scottish Journal of Geology, 41; 1, 3–11.
[[category:Groundwater and shale gas]]

Moray Firth

2026-06-24T08:43:07Z

Ajhil: /* Maps of regional variation in selected ion concentrations */

Moray Firth

2026-06-24T08:40:39Z

Ajhil: /* Reports */

{{Underconstruction}}
===Moray Firth===
Moray Firth
Coverage of baseline sampling in the Moray Firth against a simplified 1:625 000 scale geology map.
Coverage of baseline sampling in the Moray Firth against a simplified 1:625 000 scale geology map.
A total of 39 groundwater samples have been interpreted to investigate the groundwater chemistry of the Old Red Sandstone aquifers in the Moray Firth area. Of these, 17 were collected in 2007 specifically for the Baseline Scotland project. These were augmented with a further 22 samples collected during separate BGS projects since 2001. The sites were chosen so that the data would be representative of groundwater across the Old Red Sandstone aquifers in the area.

[[Image:Samplingpts_Morayshire (1).jpg|frameless|center|500px|]]

<center>'''Coverage of baseline sampling in the Moray Firth against a simplified 1:625 000 scale geology map. BGS © UKRI.'''</center>

Three main aquifer units were sampled: the Lower, Middle and Upper Old Red Sandstones in the Moray Firth area.

Download the [https://nora.nerc.ac.uk/id/eprint/10293/ Baseline Scotland: groundwater chemistry of the Old Red Sandstone aquifers of the Moray Firth area] report.

===Main findings===
The collection and interpretation of new groundwater chemistry data for the Old Red Sandstone aquifers in the Moray Firth area has led to the following conclusions:

* Groundwater in the Old Red Sandstone aquifers of the Moray Firth is generally moderately mineralised, with a median SEC of 469 μS/cm (interquartile range 341–591 μS/cm). The major ion chemistry appears to be dominated by the dissolution of carbonate cements within the aquifer and overlying deposits, and the variable influence of seawater (either directly as saline intrusion or as aerosols).
* ''Groundwater pH values'' are variable (5.33–8.06), but the median pH value is near-neutral (7.31). In general the pH of the Lower and Middle Old Red Sandstone aquifers is slightly more acidic, usually less than 7.0.
* ''Concentrations of the major cations''. The dominant cation is Ca, with a median concentration of 54.8 mg/L (interquartile range 42.5–74 mg/L). Mg and K concentrations are generally low (median 4.21 and 3.7 mg/L, respectively). The median Na is 20.6 mg/L (interquartile range 12.6–28 mg/L); however, a few samples have been affected by the proximity to the sea and have much higher concentrations (95th percentile 68 mg/L, and maximum concentration 153 mg/L).
* ''Concentrations of the major anions''. The dominant anion is bicarbonate, with a median concentration of 183 mg/L (interquartile range 183–230 mg/L). Around one third of the samples are saturated with respect to calcite. Sulphate concentrations are generally low (median 14.6 mg/L, interquartile range 7.7–36.4 mg/L), although higher concentrations are encountered in samples affected by seawater, and/or possibly by gypsum bands within the aquifer. Chloride concentrations follow broadly the same distribution as Na and have a median of 38.8 mg/L and interquartile range of 19.5–49.5 mg/L; the same few samples show high Cl concentrations as do Na.
* ''There is a large range in redox conditions across the aquifer''. Sub-oxic or mildy reducing groundwaters (where dissolved oxygen (DO) concentrations are <1 mg/L) are prevalent across much of the Upper Old Red Sandstone, and parts of the Middle Old Red Sandstone. These reducing conditions may reflect the presence of low permeability layers (often marine in origin) within the thick superficial deposits overlying the Old Red Sandstone aquifer.
* ''Concentrations of minor and trace elements'' are dominated by the redox conditions. Concentrations of Fe and Mn are relatively high, with median concentrations of 38 and 43 μg/L respectively, and 75th percentile values of 354 and 227 μg/L respectively. Concentrations are highest in the Upper Old Red sandstone outcrop, and parts of the Middle Old Red Sandstone, reflecting the reducing nature of the groundwaters.
* ''Nitrate concentrations'' are variable across the aquifer units, although median concentrations are low (1.45 mg/L TON-N or less in each aquifer). The prevalence of low oxygen conditions in the sampled groundwaters has led to denitrification, which means the relationship between land use and nitrate concentrations is less obvious than for other parts of Scotland (MacDonald et al. 2005). However, there is a clear relationship between nitrate concentrations and the Nitrate Vulnerable Zone (NVZ) that covers much of the study area, with the seven highest groundwater nitrate concentrations, ranging from 5.98 to 22.1 mg/L TON-N, all from samples taken within the NVZ. The highest median concentrations were from samples collected on land known to be used for dairy, pig or poultry farming.
* ''Concentrations of phosphorous'' range from less than detection limit up to 172 μg P/L, with an overall median of 36 μg P/L, which is in the eutrophic range for surface waters. Concentrations are generally low in the western part of the study area, and an observed relationship with the spatial pattern of F suggests that both elements may be in part derived from the dissolution of phosphate minerals, such as apatite, from the aquifer rocks. Concentrations in the eastern part of the study area are generally higher, usually in the mesotropic or eutrophic range for surface waters. The higher values may be related to land use, with P inputs from agricultural activity.

===Interpretations in terms of groundwater flow===
The information on hydrochemistry and groundwater residence times can help give an insight into groundwater flow in the Old Red Sandstone aquifers in the Moray Firth area. There is no evidence of palaeowater in the samples taken from the area; most of the groundwater are interpreted as being less than 50 years old using the SF6 data. The reducing nature of the groundwaters make it difficult to interpret the CFC data (since both CFC-11 and CFC-12 have been reduced) and get a reliable estimate of whether flow is predominantly fracture dominated or piston intergranular flow. Two samples that were not reducing appear to show piston flow; however, groundwater chemistry (in particularly nitrate) show no significant depth correlations, implying that groundwater is well mixed. A possible explanation is that piston flow occurs in the thick overlying superficial deposits, but within the sandstone fracture flow may dominate.

Carbon isotope evidence indicates the significant role of the nature of the superficial cover in impacting the groundwater chemistry, showing differences between groundwaters recharged through glaciofluvial deposits, which are likely to derive bicarbonate from silicate hydrolysis, and those recharged through marine or beach deposits, in which bicarbonate is likely to derive from dissolution of shell carbonate.

===Data===
'''Summary statistics''' 
The table and plot below provide a statistical summary of the natural variation in groundwater chemistry in the Old Red Sandstones aquifers across the Moray Firth area. Data between the 10th and 90th percentiles for each element or ion are presented, which allows the influence of outliers to be minimised. We would expect new data to plot within this range 80% of the time, with the exception of NO3-N and P, where the influence of anthropogenic activity is likely to have distorted baseline conditions throughout much of the area.

* [[Media:LowerOldRedSST.jpg|Lower Old Red Sandstone – Table of summary statistics]]
* [[Media:MiddleOldRedSST.jpg|Middle Old Red Sandstone – Table of summary statistics]]
* [[Media:UpperOldRedSST.jpg|Upper Old Red Sandstone – Table of summary statistics]]
* [[Media:piperplot (1).jpg|Piper diagrams illustrate the distribution of groundwater chemistry data for all Old Red Sandstone aquifers]]

===Lower Old Red Sandstone===
The four Lower Old Red Sandstone groundwater samples showed a range in cation dominance from Ca to Na-K. All but one are dominated by HCO3 anions, with the remaining sample strongly dominated by Cl. Dissolved oxygen and redox (Eh) values are only available for two of the samples, which were oxic. Three of the four samples had below-neutral pH values, and the median was 6.34, lower than the median for the whole Old Red Sandstone dataset. Concentrations of most major ions are lower on average than in Middle and Upper Old Red Sandstone groundwaters, except Mg which is similar. Relatively low Ca concentrations and pH values probably result from a lack of carbonate minerals in the aquifer or overlying superficial deposits, which is also reflected in the lower calcite saturation values for these groundwaters (all but one of the samples was strongly undersaturated with respect to calcite). Iron concentrations are typically low, while manganese concentrations show a larger range, with a low media value.

===Middle Old Red Sandstone===
Groundwaters from the Middle Old Red Sandstone aquifer show an overall cationic dominance by Ca, but a relatively wide spread, trending towards no dominant cation. Their anionic distribution is more restricted, strongly dominated by HCO-3, apart from a single Cl-dominated water. They show very little SO4 influence. Most of the samples are undersaturated with respect to calcite, but less strongly so than the Lower Old Red Sandstone waters.

Dissolved oxygen and Eh measurements are available for only seven of the fourteen Middle Old Red Sandstone samples, of which four are oxic and three are anoxic. The groundwaters have a higher median pH than the Lower Old Red Sandstone waters, and the highest median HCO3 concentration of the three aquifers. SEC and median Ca, Na, K and Cl concentrations are in between the average values for the Lower and the Upper Old Red Sandstone groundwaters. Concentrations of SO4 are, as for the Lower Old Red Sandstone, relatively low, while magnesium concentrations are comparable to the other two aquifers.

[[Manganese (Mn) in Scottish Groundwater | Iron and Mn concentrations]] are highly variable, from low (less than the detection limit for Fe) to high, although both show low median concentrations. The main control on the presence of high Fe and Mn is likely to be the presence of anoxic conditions within the aquifer [https://nora.nerc.ac.uk/id/eprint/9665/ (Hominik et al. 2010)].

===Upper Old Red Sandstone===
Groundwaters from the Upper Old Red Sandstone aquifer typically show very similar cation distribution, dominated by Ca in all but one case, and closely grouped. They show a wider anionic range, from HCO3 towards Cl and SO4. Most of the samples for which DO and Eh measurements are available are anoxic; only three of fourteen samples showed clearly oxic conditions. The groundwaters have the highest median pH value of the three aquifers, and a slightly lower median HCO3 concentration than the Middle Old Red Sandstone waters. The median SEC value and median concentrations of all of the major ions except Mg are also the highest of the three aquifers. SO4 concentrations in particular are noticeably higher than the other two aquifers. Iron and Mn concentrations are also highly variable, from low (less than the detection limit for Fe) to very high. The median Fe concentration is not especially high, but the median Mn concentration is more than twice the drinking water limit. The high concentrations of both of these parameters are linked to the prevalence of anoxic conditions across much of the aquifer [https://nora.nerc.ac.uk/id/eprint/9665/ (Hominik et al. 2010)].

===Maps of regional variation in selected ion concentrations===

* [[Media:pH_HCO3 (2).jpg|pH and HCO3 — Maps illustrating spatial variation in the concentration]]
* [[Media:Na_K (2).jpg|Na and K — Maps illustrating spatial variation in the concentration]]
* [[Media:Ca_Mg (2).jpg|Ca and Mg — Maps illustrating spatial variation in the concentration]]
* [[Media:Cl_SO4 (1).jpg|Cl and SO4 — Maps illustrating spatial variation in the concentration]]
* [[Media:TON_Fe.jpg|TON and Fe — Maps illustrating spatial variation in the concentration]]
* [[Media:pH_HCO3 (3).jpg|Mn and F — Maps illustrating spatial variation in the concentration]]

===Reports===
Ó Dochartaigh, B É, Smedley, P L, MacDonald, A M, and Darling, W G. 2010. [https://nora.nerc.ac.uk/id/eprint/10293/ Baseline Scotland: groundwater chemistry of the Old Red Sandstone aquifers of the Moray Firth area]. British Geological Survey Open Report, OR/10/031.

MacDonald, A M, Robins, N S, Ball, D F and Ó Dochartaigh, B É. 2005. [https://nora.nerc.ac.uk/id/eprint/12230/ An overview of groundwater in Scotland]. Scottish Journal of Geology, 41; 1, 3–11.
[[category:Groundwater and shale gas]]

File:Bedrock aquifer units.jpg

2026-06-17T13:22:29Z

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